Coated paper



lfatented Feb. 25, 1941 UNITED STATES COATED PAPER Clarence M. Loane, Hammond, Ind.. assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Original application December 16,

1936, Serial No. 116,233. Divided and flill application September 25, 1940, Serial No. 358,312

4 Claims.

This invention relates to the method of coating paper and packaging materials with hydrocarbon pro'ducts such as paraffin wax, petrolatum, and refined oils.

When paraifin wax, petrolatum, refined oils, or white oils are used to coat or impregnate paper and packaging materials it has been found that these hydrocarbon products deteriorate rapidly and form undesirable odors resembling a rancid odor. Consequently, the utility of the paper as a means for wrapping food products is greatly impaired. Even though antioxidants may have been added to the oil or wax prior to its impregnation in the paper, it has been found that the thus treated paper still has the tendency to develop rancid odors in relatively short periods 01 time.

One of the objects of my invention is to prepare a paper or packaging material, of the cellulosic type, coated with paramn wax, petrolatum, or refined mineral oils which may be used to wrap food products such as bread, butter, lard and the like. Papers prepared in accordance with my process may be stored for long periods of time without forming rancid odors. quently the food products or materials encased with the coated paper will not become contaminated with undesirable odors which result from the deterioration of the oil or wax in the paper.

I have discovered that paper is a pro-oxidant for parafiin waxes and refined mineral oils and that when such oils or waxes are used to coat or impregnate paper, their stability is quickly impaired. For example, a parafiin wax, petrolatum, or refined mineral oil which can be stored at room temperature for as long as several years before becoming rancid, will become rancid in as little as two or three months when stored as waxed, petrolatum-impregnated, or oiled paper. Furthermore, when paraflin waxes and refined oils containing a small percent of antioxidants are used to impregnate paper, it has been found that the wax or oil developed rancid odor in a much shorter time than the same wax or oil before its impregnation in the paper.

I have discovered, that by impregnating or covering the surface of paper with an antioxidant prior to the application of paraffin wax, petrolatum, refined wax, or a refined'oil that the catalytic effect of the paper upon the coating will be greatly retarded. In carrying out my invention, the paper is impregnated with an antioxidant before adding the paraflin wax or oil coating. This operation may be performed in many ways, for example, the paper is passed through an Conseaqueous solution of the antioxidant and then permitted to dry. The thus treated paper is dant may be sprayed onto the paper at any point in its process of manufacture providing precautions are taken to prevent substantial amounts of the antioxidants from being washed out of the finished product. The antioxidant may also be applied to the paper in the vapor phase; the paper being passed through a chamber containing steam and the vapor of the antioxidant to be used, e. g., beta-naphthol, In drying paper that has been impregnated with the antioxidant, precaution should be taken not to overheat the paper during the drying operation. Excessive heating during the drying operation may partly destroy the effectiveness of the antioxidant.

In the event that the particular antioxidant to be used is not sufiiciently soluble in water to prepare concentrated solutions, the paper may be soaked in a saturated aqueous solution or suspension of the antioxidant. Also, volatile solvents may be used for the antioxidants, namely, ether, alcohol and the like, or emulsified solutions of the antioxidant. In preparing a paper impregnated with catechol, I have found that by soaking the paper in a 0.1% aqueous solution of catechol for about 15 minutes, a sufficient amount of the antioxidant will difiuse into the paper to destroy the pro-oxidant effect of the paper upon the hydrocarbon coating to be applied. Solutions containing various amounts of the antioxidants, for example 1% to 0.001%, may be employed in order to impregnate the paper and particularly the surface of the paper with the desired antioxidant. Also, solutions containing an admixture of the hereinafter mentioned anti.- oxidants may also be employed.

The paraflin waxes having various melting points may be used to impregnate papers and package materials in accordance with my invention. Waxes having melting points from 122-124,,130432 and 135-138 F., are examples of waxes that may be used. Refined oils, for

example white oils, having Saybolt viscosities at F. ranging from 75 to seconds, are generally used. Petrolatums may also be used. Waxes having higher and lower melting points than those given above as well as refined oils having higher and lower viscosities than thoseamples of the alkyl phenols are tri-butyl phenol,

tertiary butyl phenol, tertiary alkyl phenols generally and octyl phenol. Examples of the polyhydroxy benzenes and derivatives are hydroquinone, pyrogallol, catechol, alkylated dihydroxy benzene such as 1:2-di-methyl-3z6-dihydroxy benzene, 1 2-di-methyl-4 5-di-hydroxy benzene, 1 :3-di-ethyl-2 5-di-hydroxy benzene, tertiary butyl catechol, ethyl pyrogallol, alkoxy hydroxy benzenes such as methoxy hydroquinone, pyrogallol-l-methyl ether, ethoxy-catechol and the like. Examples of the naphthols are alpha naphthol, beta naphthol, 1:2-di-hydroxy naphthalene and 1:4-di-hydroxy naphthalene. Examples of the aromatic amines are alpha naphthylamine, phenyl alpha naphthylamine, alkyl alpha naphthylamines such as the methyl and ethyl derivatives, polyamines such as .para phenylene di-amine. Examples of the amino.-

phenols are ortho-aminophenol, para-aminophenol, alkyl substituted aminophenols such as dimethyl para-aminophenol, di-butyl aminophenol, and di-ethyl aminocresol, aryl aminophenols such as phenyl-aminophenol, and aralkyl aminophenols such as benzyl aminophenol and the like.

The foregoing specification and examples will serve to define the scope of my invention and ake itsadvantages apparent to those skilled in the art to which it pertains. The specific antioxidants mentioned are given for fllustrative purposes and are not intended to restrict the scope of the invention. It will be evident that the invention is not limited to the specific'hydrocarbon coating materials herein described.

This application is a division of Serial No. 116,233, filed December 16, 1936.

I claim: V

1. A process of making a flexible sheet packaging material comprising first applying to the sheet packaging material a surfacing of an antioxidant which is spread over the entire surface thereof and then applying a non-antioxygenic water repellent coating material, said antioxidantbeing 15 selected from the group consisting of monohydric phenols and naphthols.

2. A process of making a flexible sheet packaging material comprising first applying to the sheet packaging material a surfacing ofan antioxidant which is spread over the entire surface thereof and then applying a non-antioxygenic water repellent coating material, said antioxidant being an allqrl phenol.

3. A process or making a flexible sheet packaging material comprising first applying to the sheet packaging material a surfacing of an antioxidant which is spread over the entire surface thereof and then applyinga non-antioxygenic water repellent coating material, said antioxidant being an amino phenol.

4. The method of preparing a hydrocarbon coated paper which is stable against oxidation which comprises impregnating the paper surface with a small amount of an antioxidant selected from the group consisting of monohydric phenols and naphthols and then coating the thus treated paper with a hydrocarbon containing material selected from the group consisting of paraffin wax, petrolatum and refined oil.

CLARENCE M. LOANE. 

